creating energy from oil sands requires so much energy that the oil companies wind up spiking greenhouse gas emissions. >> and they do it in volumes that exceed any other production of oil crude anywhere on the planet. >> elizabeth may is the director of the sierra club of canada. she takes issue not only with what the oil sands are doing to the atmosphere but to the land. the oil companies, environmentalists say, are digging up an entire province. take a helicopter ride over the mines, and you'll think you're flying over the moon after a moonquake. >> one of the reasons they can be mined the way they're mined is the "out of sight, out of mind" aspect of it. i mean, your film crew is one of the few that's gone in there to look at how devastating this is. >> even the money men have noticed. >> can't argue with it. i mean, there's no question that they've got a mess up there. i do believe that will be taken care of over time. >> the oil companies say they'll reduce greenhouse gases, and they point out they're required by canadian law to refill old mines and plant new trees, and that is hap